The present invention relates to an improved femoral hip prosthetic implant and to a process for securing a hip prosthetic implant to the proximal end of the femur.
Total hip arthroplasty, or hip replacement, during the last few decades has evolved into a standard orthopedic procedure; it is estimated that approximately 100,000 hip replacements are performed yearly in the United States and almost four times that amount world wide. Success rates are consistently reported to be greater than 90% and are accompanied by dramatic reduction in the patient's pain and disability.
While total hip replacement works well and relieves pain, it is not entirely without problems. One common problem is that the femoral implant loosens from the femoral canal. Also, in approximately 3% of the implants, post operative dislocation of the head of the femur from the acetabular cup may occur. Both of these problems, loosening of the femur, and dislocation of the hip joint--are believed to arise from an underlying problem presented by all the various techniques for performing hip arthroplasty. These techniques require the surgeon to prepare a socket in the proximal end of the femur for receiving the distal end of the implant, then to fill that socket either partially or totally with a cement, then to force the stem end portion of the implant into the prepared socket while the cement is still in a workable condition and to accurately position the implant so that its head will seat properly in the acetabular cup, all before the cement hardens.
The present invention has as a major objective the provision of a femoral implant, and a process for securing a femoral implant in the proximal end of the femur, such that the implant is accurately and stably positioned within the femur, using a simple and reproducible procedure, to achieve a uniform thickness of the cement mantle surrounding the implant and to completely fill the proximal space between the implant and the femur. Another object of the present invention is to provide an implant and procedure which, should it become necessary to replace the implant, permits the implant to be easily removed and all of the cement cleaned from the femoral canal with minimum loss of bone tissue.
These and other objects will be apparent to those skilled in this art from the following detailed description of a preferred embodiment of the invention.